A feature used in vehicles includes automated speech recognition (ASR). ASR technology enables microphone-equipped computing devices to interpret speech and thereby provide an alternative to conventional human-to-computer input devices such as keyboards or keypads. For example, vehicle telecommunications devices can be equipped with voice dialing features enabled by an ASR system. The ASR system typically includes one or more microphones to receive speech from an occupant of a vehicle.
Another feature used in vehicles includes hands-free calling or hands-free telecommunication (HFT). HFT enables a user to initiate a telephone call by a push of a button and/or by ASR-enabled voice dialing, and enables the user to carry out the call without having to hold a telephone. In contrast to an ASR system, an HFT system is relatively sensitive to vehicle noise and, thus, typically includes a hands-free algorithm having parameters that are tuned for good performance in a particular vehicle cabin and under various vehicle operating conditions.
Microphones for ASR and HFT are usually located in a forward portion of a passenger compartment of the vehicle, such as in a rear view mirror assembly or in a headliner. Such a forward mounted microphone is satisfactory to enable reliable ASR and/or HFT for a driver. But the forward mounted microphone may not be satisfactory to enable reliable recognition of speech from other passengers in front and rear seating positions. Accordingly, some systems deploy a plurality of individual microphones in a vehicle interior; with one microphone and associated pushbutton located at each seating position. But this approach unnecessarily adds cost and complexity to the system.
A further feature used in vehicles includes active noise control (ANC) to reduce noise produced by vehicle engines, tires, ventilation systems, and the like. ANC systems may use a controller, microphones to sense objectionable noise and transmit the noise to the controller for processing and output of a cancellation waveform, and a speaker to receive the cancellation waveform and output the waveform to cancel the objectionable noise. ANC microphones are tuned to sense low frequency vehicle noise and, thus, are not considered suitable for use with ASR or HFT.